From 42ca83d3c0b5d6e4ccc67a5754b7889bad8ca14a Mon Sep 17 00:00:00 2001
From: andig <cpuidle@gmx.de>
Date: Sat, 3 Dec 2022 15:07:12 +0100
Subject: [PATCH] Sessions: fix odometer not persisted

---
 core/db/db.go             |  3 ---
 core/db/session.go        |  9 -------
 core/loadpoint.go         | 15 ++++++++---
 core/loadpoint_session.go | 55 +++++++++++++++++++++++++--------------
 4 files changed, 46 insertions(+), 36 deletions(-)

diff --git a/core/db/db.go b/core/db/db.go
index 9aee1d250..4222e24c2 100644
--- a/core/db/db.go
+++ b/core/db/db.go
@@ -1,8 +1,6 @@
 package db
 
 import (
-	"time"
-
 	serverdb "github.com/evcc-io/evcc/server/db"
 	"github.com/evcc-io/evcc/util"
 	"gorm.io/gorm"
@@ -35,7 +33,6 @@ func New(name string) (*DB, error) {
 func (s *DB) Session(meter float64) *Session {
 	t := Session{
 		Loadpoint:  s.name,
-		Created:    time.Now(),
 		MeterStart: meter,
 	}
 
diff --git a/core/db/session.go b/core/db/session.go
index 9a94a1ff9..6aff7b518 100644
--- a/core/db/session.go
+++ b/core/db/session.go
@@ -31,15 +31,6 @@ type Session struct {
 	ChargedEnergy float64   `json:"chargedEnergy" csv:"Charged Energy (kWh)" gorm:"column:charged_kwh"`
 }
 
-// Stop stops charging session with end meter reading and due total amount
-func (t *Session) Stop(chargedWh, total float64) {
-	if chargedEnergy := chargedWh / 1e3; chargedEnergy > t.ChargedEnergy {
-		t.ChargedEnergy = chargedEnergy
-	}
-	t.MeterStop = total
-	t.Finished = time.Now()
-}
-
 // Sessions is a list of sessions
 type Sessions []Session
 
diff --git a/core/loadpoint.go b/core/loadpoint.go
index d68f156a8..e424710dd 100644
--- a/core/loadpoint.go
+++ b/core/loadpoint.go
@@ -387,7 +387,12 @@ func (lp *LoadPoint) evChargeStartHandler() {
 	// soc update reset
 	lp.socUpdated = time.Time{}
 
-	lp.startSession()
+	// set created when first charging session segment starts
+	lp.updateSession(func(session *db.Session) {
+		if session.Created.IsZero() {
+			session.Created = lp.clock.Now()
+		}
+	})
 }
 
 // evChargeStopHandler sends external stop event
@@ -432,15 +437,17 @@ func (lp *LoadPoint) evVehicleConnectHandler() {
 
 	// immediately allow pv mode activity
 	lp.elapsePVTimer()
+
+	// create charging session
+	lp.createSession()
 }
 
 // evVehicleDisconnectHandler sends external start event
 func (lp *LoadPoint) evVehicleDisconnectHandler() {
 	lp.log.INFO.Println("car disconnected")
 
-	// ensure session is persisted and closed before vehicle is changed
-	lp.stopSession()
-	lp.finalizeSession()
+	// session is persisted during evChargeStopHandler which runs before
+	lp.clearSession()
 
 	// phases are unknown when vehicle disconnects
 	lp.resetMeasuredPhases()
diff --git a/core/loadpoint_session.go b/core/loadpoint_session.go
index f37d8f28f..c14bda722 100644
--- a/core/loadpoint_session.go
+++ b/core/loadpoint_session.go
@@ -1,6 +1,8 @@
 package core
 
 import (
+	"time"
+
 	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/core/db"
 )
@@ -20,39 +22,50 @@ func (lp *LoadPoint) chargeMeterTotal() float64 {
 	return f
 }
 
-func (lp *LoadPoint) startSession() {
+// createSession creates a charging session. The created timestamp is empty until set by evChargeStartHandler.
+// The session is not persisted yet. That will only happen when stopSession is called.
+func (lp *LoadPoint) createSession() {
 	// test guard
-	if lp.db == nil {
+	if lp.db == nil || lp.session != nil {
 		return
 	}
 
-	if lp.session == nil {
-		lp.session = lp.db.Session(lp.chargeMeterTotal())
+	lp.session = lp.db.Session(lp.chargeMeterTotal())
 
-		if lp.vehicle != nil {
-			lp.session.Vehicle = lp.vehicle.Title()
-		}
-
-		if c, ok := lp.charger.(api.Identifier); ok {
-			if id, err := c.Identify(); err == nil {
-				lp.session.Identifier = id
-			}
-		}
-
-		// TODO remove
-		lp.log.DEBUG.Println("session started")
-
-		lp.db.Persist(lp.session)
+	if lp.vehicle != nil {
+		lp.session.Vehicle = lp.vehicle.Title()
 	}
+
+	if c, ok := lp.charger.(api.Identifier); ok {
+		if id, err := c.Identify(); err == nil {
+			lp.session.Identifier = id
+		}
+	}
+
+	// TODO remove
+	lp.log.DEBUG.Println("session started")
 }
 
+// stopSession ends a charging session segment and persists the session.
 func (lp *LoadPoint) stopSession() {
 	// test guard
 	if lp.db == nil || lp.session == nil {
 		return
 	}
 
-	lp.session.Stop(lp.getChargedEnergy(), lp.chargeMeterTotal())
+	// abort the session if charging has never started
+	if lp.session.Created.IsZero() {
+		// TODO remove
+		lp.log.DEBUG.Println("session aborted")
+		return
+	}
+
+	lp.session.Finished = time.Now()
+	lp.session.MeterStop = lp.chargeMeterTotal()
+
+	if chargedEnergy := lp.getChargedEnergy() / 1e3; chargedEnergy > lp.session.ChargedEnergy {
+		lp.session.ChargedEnergy = chargedEnergy
+	}
 
 	// TODO remove
 	lp.log.DEBUG.Println("session stopped")
@@ -62,6 +75,7 @@ func (lp *LoadPoint) stopSession() {
 
 type sessionOption func(*db.Session)
 
+// updateSession updates any parameter of a charging session and persists the session.
 func (lp *LoadPoint) updateSession(opts ...sessionOption) {
 	// test guard
 	if lp.db == nil || lp.session == nil {
@@ -78,7 +92,8 @@ func (lp *LoadPoint) updateSession(opts ...sessionOption) {
 	lp.db.Persist(lp.session)
 }
 
-func (lp *LoadPoint) finalizeSession() {
+// clearSession clears the charging session without persisting it.
+func (lp *LoadPoint) clearSession() {
 	// test guard
 	if lp.db == nil {
 		return